*4.11. Oxygen Permeability of CS/PVOH/HNT and CS/PVOH/TO@HNT Films*

ASTM D 3985 method (23 ◦C and 0% RH) was followed to estimate the oxygen transmission rate (OTR). OTR values in cc O2·m−<sup>2</sup> ·day−<sup>1</sup> achieved using an (8001, Systech Illinois Instruments Co., Johnsburg, IL, USA) oxygen permeation analyzer. The oxygen permeability coefficient Pegas (cm2/s), was estimated following Equations (4) and (5) of the number [50] referenced paper and according to the theory described in the literature [68].
